Treatment of filaments, threads, and the like



are 17, 1%6. w. l. TAYLOR 2,034,009

TREATMENT OF FILAMENTS, THREADS AND THE LIKE Filed Nov. 6, 1931 FIQJ- FIGJS- mi WILLIAM I TAYLOR INVENT R Patented Mar. 17, 1936 UNITED STAT ATET OFFICE TREATMENT OF FILAMENTS, THREADS, AND THE LIKE William Ivan Taylor, Spondon, near Derby, England, assignor to Celanese Corporation of America, a corporation of Delaware 8 Claims.

This invention relates to improvements in the treatment of filaments, threads, ribbons, films and the like with liquids and is primarily concerned with a new process for the production of filaments, threads, ribbons, films and other products by wet or semi-wet spinning processes.

According to the invention liquids are applied to filaments, threads and the like by the longitudinal travel of the filaments and the like in contact with and transverse to a surface supplied with a film of liquid. The invention is most valuable in its application to the spinning of artificial filaments and other products, and in this application a spinning solution is extruded through a coagulating medium in such a way that the filaments carry with them an amount of liquid insufiicient to cause them to cling together. Thus the spinning solution may be extruded through a film of coagulating liquid of limited thickness.

In the production of filaments, threads and the like by normal wet spinning processes the filaments and the like emerging from the coagulating bath carry with them a large bulk 25 of liquid which causes them to cling together so as to render the drying of the filaments or threads a difficult and slow operation. This considerably restricts the maximum speed at which wet spinning processes may be operated. By the present invention, wherein the spinning solution is extruded through an amount of liquid insuflicient to cause the filaments and like products to cling together, spinning speeds very much higher than those hitherto practicable may be attained, for example spinning speeds of the order of those employed in dry-spinning operations, i. e. speeds of 150 to 200 or 300 or 400 metres per minute or more. By this means the advantages inherent in wet spinning processes are obtained simultaneously with the particular advantage attaching to dry spinning processes, namely high speed of spinning.

In order to extrude the spinning solution through a film of liquid the exterior surface of the spinning nozzle may be continuously supplied with such a liquid so as to form a film through which the spinning solution has to be extruded. The new spinning nozzles provided with such means for supplyng liquid form part of the present invention.

In its application to the manufacture of artificial filaments and like products the invention may be carried into effect in a large number of ways, and the following methods are only instanced as examples of methods of achieving the advantages of the invention. In one method of carrying the invention into effect, the under side of a spinning nozzle adapted tospin downwards, though not necessarily vertically downwards, is covered and continuously supplied with 5 an adhering film of coagulating liquid. The film of coagulating liquid before spinning commences completely covers the extrusion orifices of the nozzle, and when spinning is started the filaments falling or being drawn through the film 10 of coagulating liquid carry with them a small quantity of the liquid insufficient by reason of the surface tension of the liquid itself to cause them to cling together. It will be appreciated that the maximum permissible thickness of the 16 film of coagulating liquid will be dependent on the size of the jet orifices and therefore on the denier of the filaments being spun and also upon the distance apart of the individual jet orifices, and to a lesser extent on the coefficient of the 20 surface tension between the coagulating liquid and the incipient filaments. Conveniently the jet orifices may be formed at the centre or towards the centre, say in a ring round the centre,

of a hemispherical nozzle, the upper edge of the hemispherical nozzle being flanged to fit into a cup-shaped member supplied with coagulating liquid. The cup-shaped member may, for example, be notched at intervals round its circumference, so as to permit the coagulating liquid to flow slowly in the form of a film round the entire outside surface of the hemispherical nozzle. Preferably the rate at which the coagulating liquid is supplied to the outside surface of the nozzle during spinning is adjusted so that the film of coagulating liquid does not tend to form in drops over the jet orifices or in other words the filaments are extruded at a sufficient rate to carry away the whole of the coagulating liquid supplied. It will thus be seen 40 that the filaments are formed as is usual in the wet spinning process in a body of coagulating liquid, and in this preferred form they carry this coagulating liquid as a kind of sheath or outside layer for some distance during their travel. They may then be treated according to dry spinning processes so as to evaporate the solvent from the spinning solution and also to evaporate the coagulating liquid supplied to the nozzle.

The above method of carrying the invention into effect consists in bringing a body of coagulating liquid from the outside towards the ring of spinning jets or orifices. The invention is not of course limited tosuch an arrangement of the jet orifices or to such a means of bringing the coagulating liquid thereto. For example the jet orifices may be spread over a substantially fiat surface or over a surface of any convenient shape, but preferably they are so arranged that substantially equal amounts of coagulating liquid are capable of contacting with each of the filaments in the moment of their formation. Another method of carrying the invention into effect consists in supplying coagulating liquid to the inside of a ring of jet orifices, so as to cover the nozzle face with a film as before. Or again a coagulating liquid may be supplied both from the inside and outside of a. ring of orifices. Further the orifices may be arranged in line along a wedge-shaped jet, i. e. a jet of more or less triangular crosssection. The coagulating liquid may then be caused to flow in the form of a film down the outside of the two faces of the wedge towards the edge along which the jet orifices are arranged. Or again a similar arrangement may be adopted in the case of a single line or a plurality of lines of orifices arranged in a nozzle having a semicylindrical shape. Thering-shaped nozzles described in U. S. Patent No. 1,883,423 filed 2nd January, 1929 may be considered to be jets of this type and are very suitable for use in the present invention. The coagulating liquid may be supplied to the interior of the circular line of jets by way of the recessed portion of the nozzle or more advantageously to both the exterior and the interior of the jets.

A further means of carrying the invention into effect consists in continuously supplying with a film of coagulating liquid of the requisite thickness the upper surface of a spinning nozzle adapted to spin upwardly. The nozzle may for example be planar or concave or even convex. In the last case the coagulating liquid may be supplied to the centre of the jet and in the first case either to the outside or to the centre or both, while it is most convenient in the case of a concave jet to supply the liquid from the exterior edges of the jet. As in the case of downward spinning, line jets may be used and suitable methods of supplying the coagulating liquid will be obvious from the above description.

In order to obtain a uniform evaporation of the solvent contained in the spinning solution it is preferable that the coagulating liquid supplied to the nozzle should be of lower volatility at the spinning temperature than the solvent of the spinning solution. Further it is preferable that it should not act so as to exercise too great a precipitating action upon the filaments during their formation unless a matt effect is desired. For this reason I prefer to employ as the coagulating liquid a liquid having a high plasticizing power for the cellulose acetate or other cellulose ester or ether or other base of the spinning solution, and I refer broadly in this connection to the coagulating liquids described in U. S. applications S. Nos. 402,785 filed 26th October 1929 and 418,414 filed 3rd January 1930. For example solvents, preferably organic and preferably of relatively low volatility, may be employed in aqueous or alcoholic solution in relatively high concentration. For instance ethyl lactate, diacetone alcohol, diethyl tartrate, monoand di-acetin, dioxane, lactic acid and the like may be applied in aqueous or alcoholic solution in a concentration of 25-65%. Liquid plasticizing agents, as for example tricresyl phosphate or the isomeric xylene mono-methyl sulphonamides, or liquid mixtures of plasticizing agents with solvents and/or nonsolvents for the cellulose derivative may also be employed.

Figures 1 to 8 of the accompanying drawing illustrate forms of nozzle in accordance with the present invention, Figures 1, 3, 5 and 7 being elevations partly in section, and Figures 2, 4, 6 and 8 being the corresponding plans or inverted plans. Fig. 9 shows a side elevational view of a modified arrangement for carrying out the present invention.

Referring to Figures 1 and 2 a hemispherical spinning jet I 0 secured in the usual manner to a spinning head is adapted to extrude filaments H through a film of liquid adhering toits convex surface and supplied from a trough l2 surrounding the jet. In Figure 2 the jet holes are shown at l3 and the trough l2 supplies the liquid by means of the notches Id. The size of the notches [4 determines the rate at which the coagulating liquid is supplied from the trough l2 to the filaments H.

Figures 3 and 4 illustrate a nozzle adapted to spin a line of filaments. The nozzle I5 is wedgeshaped and has the spinning orifices l6 distributed along its lower edge. The jet is provided with a trough l! in which notches [8 are cut so as to allow a film of liquid to trickle outside the surface of the nozzle in a similar manner to that described with reference to Figures 1 and 2.

Figures 5 and 6 illustrate a nozzle adapted for upward spinning. On the concave nozzle l9 provided with jet holes 20 is mounted an annular trough 2| adapted to contain the coagulating medium and provided with holes 22 which supply the coagulating liquid in the form of a thin film to the concave surface of the nozzle. For ease of starting up the nozzle i9 may be attached to the spinning head by means of a swivel joint. The nozzle is started up so as to spin downwardly, is then turned upwards by means of the swivel joint, and the trough 2| then filled with the coagulating liquid. Spinning then proceeds continuously.

Figures '7 and 8 illustrate the type of nozzle claimed in U. S. Patent No. 1,883,423 provided with means for supplying a film of coagulating liquid in accordance with the present invention. The nozzle 23 provided with an annular troughshaped portion 24 with a ring of jet holes 25 is supplied with spinning solution through the ducts 26. The interior tube 2'! supplies coagulating liquid through a series of holes 28 to the interior surface 29 inside the ring of jet holes. The rate of flow of the coagulating liquid through the tube 21 and the holes 28 may be suitably adjusted by providing the source of supply with a needle valve or other means of regulation.

As already indicated the filaments or other products after passage through the film or other thin layer of coagulating liquid may be treated according to dry spinning processes, especially in the case of spinning solutions containing cellulose acetate or other cellulose ester or ether, in which application the present invention is the most valuable. Other cellulose esters and ethers which may be contained in the spinning solution include cellulose formate, cellulose propionate, cellulose butylrate, cellulose nitrate, methyl cellulose, ethyl cellulose and benzyl cellulose. The filaments after having been'dried, for example in an ordinary dry spinning cell or metier, may be wound by any suitable methods, for example directly on bobbins in or outside the spinning cell, or may be twisted and wound, for example by means of cap spinning devices, see U. S. Patent No.

1,731,317, or a ring spinning device or other suitable means.

As already indicated, though the invention is of greatest value in its application to the spinning of artificial filaments and the like, it is by no means limited thereto, since it affords broadly a new means of applying liquids in limited quantities to filaments, threads or the like whether they are being formed in the process of applying the liquid or whether they have already been formed. For example the new process may be applied to the sizing or dyeing of continuous lengths of filaments or threads, and particularly filaments or threads of natural silk or of artificial silk, whether of the cellulosic type or of the cellulose derivative type. Thus for instance a row of filaments or threads, proceeding for example from a suitable creel or from a line of spinning jets, may be caused to contact with the lower edge of an inclined surface or of a segment of a cylindrical surface or the like supplied continuously on its lower or upper side with a film or thin layer of a size or dyeing composition or other liquid to be applied, the filaments or threads thereby being caused to carry the liquid away from the surface. Preferably the lower edge of such a surface is provided or formed with guides so as to maintain the spacing of the filaments or threads and secure uniform application of the liquid. For example the lower edge of the surface may be formed as a series of teeth. By this means a predetermined quantity of liquid may be applied to the filaments or threads with great accuracy.

Figure 9 illustrates such an application of the invention. An inclined member 36 is fitted with a trough 3| provided with holes or notches as described above adapted to permit liquid to trickle down the outside of the member 30. Filaments, yarns or the like 32, to which it is required to apply a suitable sizing, dyeing or other liquid, are passed in contact with the lower end 33 of the member 30 which is provided with a series of notches adapted to separate the filaments or yarns 32 from each other, if such separation is desired. Preferably the filaments or yarns 32 are bent at a small angle on passing the lower edge 33 so as to maintain a good contact.

What I claim and desire to secure by Letters Patent is:-

1. Process for the production of artificial filaments comprising extruding a spinning solution containing an organic derivative of cellulose through a nozzle the exterior surface of which is continuously supplied with a film of a coagulating liquid, and completing the setting of the products in an evaporative medium.

2. Process for the production of artificial filaments comprising extruding a solution of organic derivatives of cellulose in a volatile solvent or solvent mixture through a nozzle, the exterior surface of which is continuously supplied with a film of coagulating liquid, and completing the setting of the products in an evaporative medium.

3. Process for the production of artificial filaments comprising extruding a solution of organic derivatives of cellulose in a volatile solvent or solvent mixture downwards through a nozzle, the under surface of which is supplied with a film of a coagulating liquid consisting of a strong solution of a solvent for the cellulose derivative, and completing the setting of the filaments in an evaporative medium.

4. Process for the production of artificial filaments comprising extruding a solution of cellulose acetate in a volatile solvent or solvent mixture through a nozzle, the exterior surface of which is continuously supplied with a film of a coagulating liquid which is less volatile than the solvent or solvent mixture of the solution, and completing the setting of the products in an evaporative medium.

5. Process for the production of artificial filaments comprising extruding a solution of cellulose acetate in a volatile solvent through a nozzle the exterior surface of which is continuously supplied with a film of a coagulating liquid consisting of a strong solution of a solvent for cellulose acetate, and completing the setting of the products in an evaporative medium.

6. Process for the production of artificial filaments comprising extruding a solution of cellulose acetate in a volatile solvent through a nozzle, the exterior surface of which is continuously supplied with a film of a liquid selected from the group consisting of aqueous solutions of diacetone alcohol, ethyl lactate, and diethyl tartrate in concentration of 25-65%.

7. Process for the production of artificial filaments comprising extruding a solution of cellulose acetate in a volatile solvent downwards through a nozzle, the exterior surface of which is continuously supplied with a film of a coagulating liquid selected from the group consisting of aqueous solutions of diacetone alcohol, ethyl lactate and diethyl tartrate in concentration of 25-65%.

8. A spinning nozzle having a plurality of orifices and provided with a container contacting with its exterior surface and adapted to maintain a thin film of liquid on said surface.

WILLIAM IVAN TAYLOR. 

